The relationship of graded, dietary cadmium intake levels to biochemical parameters associated with cadmium toxicity will be determined in rats and chicks. Cadmium uptake, calcium, copper and zinc concentration changes and enzyme activities will be investigated as a function of dose level in numerous tissues and will be correlated to the degree of toxicity. The mechanisms and factors influencing the synthesis of cadmium binding protein in liver and kidney will be investigated in detail. The mechanisms and factors involved in intestinal cadmium absorption will be studied, in vivo. The influence of calcium and vitamin D at various dietary intake levels will be investigated. the functional significance of cadmium binding to intestinal mucosal cell proteins will be investigated as well. The effect of cadmium on calcium and bone metabolism will be extensively investigated. The intestinal absorption of calcium will be investigated with in situ duodenal loops. The influence of cadmium on the renal mitochondrial enzyme 25-hydroxycholecalciferol-1-hydroxylase and 1, 25-dihydroxycholecalciferol synthesis will be extentively investigated.